Astrophysics > Earth and Planetary Astrophysics

Title:
The Colors of Extreme Outer Solar System Objects

Abstract: (Abridged) Thirty-three objects with possible origins beyond the Kuiper Belt
edge, very high inclinations, very large semi-major axes or large perihelion
distances were observed to determine their surface colors. All three objects
that have been dynamically linked to the inner Oort cloud (Sedna, 2006 SQ372,
and 2000 OO67) were found to have ultra-red surfaces (S~25). Ultra-red material
is generally associated with rich organics and the low inclination "cold"
classical Kuiper Belt objects. The observations detailed here show very red
material may be a more general feature for objects kept far from the Sun. The
recently discovered retrograde outer Solar System objects (2008 KV42 and 2008
YB3) and the high inclination object (127546) 2002 XU93 show only moderately
red surfaces (S~9), very similar to known comets. The extended or detached disk
objects, which have large perihelion distances and large eccentricities, are
found to have mostly moderately red colors (10 < S < 18). The colors of the
detached disk objects, including the dynamically unusual 2004 XR190 and 2000
CR105, are similar to the scattered disk and Plutino populations. Thus the
detached and scattered disk likely have a similar mix of objects from the same
source regions. Outer classical belt objects, including 1995 TL8, were found to
have very red surfaces (18 < S < 30). The "cold" classical belt, outer
classical belt and inner Oort cloud appear to be dominated by ultra-red objects
(S > 25) and thus don't likely have a similar mix of objects as the scattered
disk, detached disk and Trojan populations. A possible trend was found for the
detached disk and outer classical belt in that objects with smaller
eccentricities have redder surfaces irrespective of inclinations or perihelion
distances. There is also a clear trend that objects more distant appear redder.